How do you fight the Niefel giants?

[Lazy_Perfectionist]

From the game itself.
Fatigues
Animate Skeleton (1): -30
Animate Dead (1): -20
Raise Skeletons (5): -40
Raise Dead (10): -40

Javelins? Nah. With a protection of 14 and no access to Armor of Achilles... If they've got an earth bless you're out of luck. For missiles, defense doesn't matter. Just the shield's parry and fatigue.

If you've got a race that combines hot and death dominions, its rather easy to starve them out- just be aware of the catches. 4 food apiece. One shaman forged bag of endless wine can support 12. But you'll be able to identify that problem after they steamroll any outer 1 point PD.

If you're going to war with them, it may pay to raise taxes in _your_ nearby provinces, so as to raise unrest and prevent them from gaining funds there or being effective patrollers.

As Ctis, I had some effectiveness against Abysia with Black Servant, Summon Shadesx2, Rod of the Leper King- though I didn't go far enough. I wasted gems on Wights and Bane Venom Charms, rather than going in wholly with one strategy. It may be worth trying against Neifelheim. Their province defense has poor attack and protection even for 20+ points (pg 114) and is pretty skimpy in quantity. Some support can ruin this tactic, but its a pretty expensive option for Jotunheim.